docs: def send_raw(self, string):
          """Send raw string to the server, via the asyncio transport.
  
          The string will be padded with appropriate CR LF.
          """
          log.debug('RAW: {}'.format(string))
          if self.transport is None:
              raise ServerNotConnectedError("Not connected.")
  
          self.transport.write(self._prep_message(string))